Additive manufacturing is utilized to fabricate 3-dimensional (3D) parts or products by adding layer-upon-layer of material. Additive manufacturing utilizes 3D-modeling (Computer-Aided Design or CAD) software, computer-controlled additive-manufacturing equipment, and raw materials in powder or liquid form. Additive manufacturing encompasses a wide variety of technologies and incorporates a wide variety of techniques, such as, for example, laser freeform manufacturing (LFM), laser deposition (LD), direct metal deposition (DMD), laser metal deposition, laser additive manufacturing, laser engineered net shaping (LENS), stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), multi jet modeling (MJM), 3D printing, rapid prototyping, direct digital manufacturing, layered manufacturing, and additive fabrication. Moreover, a variety of raw materials may be used in additive manufacturing to create products. Examples of such materials include plastics, metals, concrete, and glass.
One example of an additive-manufacturing system is a laser additive-manufacturing system. Laser additive manufacturing includes spraying or otherwise injecting a powder or a liquid into a focused beam of a high-power laser or nexus of a plurality of high-powered lasers under controlled atmospheric conditions, thereby creating a weld pool. The resulting deposits may then be used to build or repair articles for a wide variety of applications. The powder injected into the high-power laser beam may be comprised of a wide variety of materials that include, for example, metal, plastic, etc.
Articles formed by additive manufacturing may require surface processing to provide a more desirable product. One example of surface processing includes smoothing or otherwise reducing the roughness of the product's surface. Surfaces produced by additive manufacturing may have rough surface finishes, e.g., on the order of about 600-1000 microinches Ra. Such rough surfaces may have several undesirable effects. For example, parts having a rough surface finish have limited applications in cyclical-loading environments due to stress risers typically associated with high surface roughness. Additionally, rough surfaces may impede the use of cost-saving, non-destructive inspection systems because rough surface finishes generate high levels of noise in such systems. Examples of inspection systems include NDI, NDT, Die inspection, CAT scanning, X-ray, etc. When used on parts having relatively smooth surfaces, non-destructive inspection methods are widely recognized as cost-effective and accurate tools for identifying structural deficiencies in such parts.
To improve the surface finish of a part fabricated with additive-manufacturing equipment, separate post-processing steps must be undertaken at processing location using conventional surface-finishing equipment and techniques. However, due to the complexity of some parts, post-processing of surfaces thereof may be cumbersome, expensive, and time consuming. In addition, conventional post-processing surface-finishing methods may be ineffective for reducing the surface roughness of the interior surfaces of some complex parts, resulting in products with less than desirable properties.